In recent years, FTTH (Fiber To The Home) designed to provide diverse information including broadcast information, communication information, etc. by connecting an optical fiber to an ordinary home is increasingly used at an apartment home and an ordinary housing. The optical cable in the FTTH system is extended to a home, one end of which is terminated with an optical fiber connector. The FTTH worker sets an optical cable a little longer about a few meters than an actual length in consideration with a splice between optical fibers and then is extended to a home. The worker cuts off an optical fiber by a needed length, and assemblies an optical fiber connector at its end and connects the connector with an optical adapter, thus installing the optical fiber.
The prior art patents 1 to 6 discloses diverse technologies with respect to an optical fiber connector coupled to an optical adapter.
One of the ordinary optical fiber connector is disclosed in a construction site assembling type optical connector of Korean patent registration publication No. 10-0669947 the invention of which is directed to connecting an end of a ferrule optical fiber with an end of a main optical fiber. The above patent discloses a splice method formed of a mechanical splice method connecting a main cable alignment member accommodating an end of a ferrule optical fiber and a, end of a main optical fiber, and a fusion splice method fusion-connecting an end of a ferrule optical fiber and an end of a main optical fiber by using an is optical fiber fusion connector and reinforcing a fusion splice part with a reinforcing sleeve formed of a thermal contraction tube (refer to prior arts 3 to 6).
The present invention is directed to a fusion splice method, and the optical fiber connector of the fusion splice method comprises a ferrule 1 formed of a ferrule optical fiber, an elastic member 2 elastically supporting the ferrule, a plug frame 4 accommodating the ferrule and elastic member, a stopper 3 installed at the plug frame and fixing the ferrule and the elastic member at the plug frame, a reinforcing sleeve 5 reinforcing the fusion splice part of an end of the ferrule optical fiber and an end of the main optical fiber, a plug handle 6, and a boot 7.
The optical fiber connector of the fusion splice method is characterized in that the ferrule I elastically by an elastic member, thus moving within a range set by the elastic member 2. When the ferule moves within a range set by the elastic member, an adhesion state between the ferrule body 1a and the ferrule optical fiber 1b might be worsened, or the ferrule optical fiber might be disconnected, which leads to a faster bending of part 1c of the ferrule optical fiber.
As shown in FIG. 1B, when the ferrule moves within a range set by the elastic member 2 by means of an external force, part 1b′ of the ferrule optical fiber 1b between the ferrule body 1a and the reinforcing sleeve 5 bends, and the frequent movement of the ferrule body 1a contributes to causing a failure in the adhesion state between the ferrule body and the ferrule optical fiber, and the ferrule optical fiber might be disconnected, and when external force is applied to the ferrule body 1a, part of the ferrule optical fiber bends, and part of the shorter ferrule optical fiber bends, which expedites bending, thus causing a lot of problems in the efficiency of the optical fiber.
In the optical fiber connector of a conventional fusion splice method, when a fusion splice part is reinforced by heating a reinforcing sleeve formed of a thermal contraction tube, an adhesive used to integrally form a ferrule body and a ferrule optical fiber melts down, which leads to a transformation. In order to prevent the above problem, it is needed to make the ferrule exposed in minimum when assembling the optical fiber connector.
The cold peeling (at room temperature) is mainly performed when peeling a ferrule optical fiber in such a manner that the ferrule can be exposed, in minimum, to heat, so an adhered part of the ferrule might hurt as a large force (weight) is applied in the course of peeling of the ferrule optical fiber or the ferrule optical fiber is disconnected.
The problems of the conventional art will be described using the cited prior arts.
The optical fiber disclosed in the cited prior art 3 of Korean patent publication number 10-2009-0083373 is directed to obtaining compactness. A ferrule 7 and a reinforcing sleeve 15 are very close to each other. When it is intended to heat for a thermal contraction of a reinforcing sleeve, an adhesive used to integrally form an optical fiber to a ferrule used to be transformed.
The optical fiber disclosed in Japanese patent publication number 2008-225461 in the cited prior art 6 is characterized in that a protruded portion of a fixture coupled to a frame is provided, and an integrated construction is achieved in the course of a thermal contraction of a reinforcing sleeve, thus enhancing a tensional force. When a reinforcing sleeve is thermally contracted and then becomes integral with the protruded portion of the fixture, the fixture and the optical fiber of the ferrule become integral by means of the reinforcing sleeve. As shown in FIG. 1, when force (weight) is applied to the ferrule of the front side of the connector, the ferrule moves in a longitudinal direction of the optical fiber by means of the elastic member. At this time, a bending phenomenon occurs at a part 1b′ of the shorter ferrule optical fiber 1b, so the optical fiber is disconnected, and short circuit problem occurs. Since a sharp angle bending occurs, a signal transmission loss might fast increase.
Te optical connectors of the prior art documents 3, 5 and 6 are directed to peeling the optical fibers at the factory, assembling to a ferrule with an adhesive and cutting and supplying the same to a construction site. When they are supplied in a non-peeled state, the ferrule optical fiber formed of ferrule and optical fiber which are bonded by an adhesive is needed to be peeled off at a construction site. In this case, a bonded portion becomes weak due to the weight occurring during peeling, so a transformation or short circuit problem occurs.
In addition, when the ferrule is peeled off from an optical fiber at a factory and an adhesive is bonded, and a necessary cutting is performed and supplied to a construction site, a manufacture cost increases due to a hard work, and a short circuit problem might occur when doing such works at the construction site.
The peeled optical fiber might be exposed to the air for a long time, so it might be contaminated by moisture or optical pollutant materials.
In order to overcome the above-described problems, the Japanese patent publication number 2009-69607 of the prior art document 5 discloses an invention on a packing technology providing a peeled optical fiber. In case that the optical fiber is supplied in a packed state, the manufacture cost increases, and since the entire volume of the products increase, which results in increasing transportation cost.
The reinforcing sleeve of FIG. 2 is directed to using a conventional optical connector formed of a double tube structure consisting of two thermal contraction tubes of an inner side tube 5a and an outer side tube 5b in which a thermal contraction time increases.